target/linux/brcm2708/patches-4.4/0095-drm-vc4-Drop-struct_mutex-around-CL-validation.patch

   1 From 775a3408d94a474101066ac8dd8939a4cd5c793a Mon Sep 17 00:00:00 2001
   2 From: Eric Anholt <eric@anholt.net>
   3 Date: Mon, 19 Oct 2015 08:44:35 -0700
   4 Subject: [PATCH] drm/vc4: Drop struct_mutex around CL validation.
   5
   6 We were using it so that we could make sure that shader validation
   7 state didn't change while we were validating, but now shader
   8 validation state is immutable.  The bcl/rcl generation doesn't do any
   9 other BO dereferencing, and seems to have no other global state
  10 dependency not covered by job_lock / bo_lock.
  11
  12 Fixes a lock order reversal between mmap_sem and struct_mutex.
  13
  14 Signed-off-by: Eric Anholt <eric@anholt.net>
  15 ---
  16  drivers/gpu/drm/vc4/vc4_gem.c | 12 ++++--------
  17  1 file changed, 4 insertions(+), 8 deletions(-)
  18
  19 --- a/drivers/gpu/drm/vc4/vc4_gem.c
  20 +++ b/drivers/gpu/drm/vc4/vc4_gem.c
  21 @@ -244,13 +244,15 @@ static void
  22  vc4_queue_submit(struct drm_device *dev, struct vc4_exec_info *exec)
  23  {
  24         struct vc4_dev *vc4 = to_vc4_dev(dev);
  25 -       uint64_t seqno = ++vc4->emit_seqno;
  26 +       uint64_t seqno;
  27         unsigned long irqflags;
  28
  29 +       spin_lock_irqsave(&vc4->job_lock, irqflags);
  30 +
  31 +       seqno = ++vc4->emit_seqno;
  32         exec->seqno = seqno;
  33         vc4_update_bo_seqnos(exec, seqno);
  34
  35 -       spin_lock_irqsave(&vc4->job_lock, irqflags);
  36         list_add_tail(&exec->head, &vc4->job_list);
  37
  38         /* If no job was executing, kick ours off.  Otherwise, it'll
  39 @@ -608,8 +610,6 @@ vc4_submit_cl_ioctl(struct drm_device *d
  40         exec->args = args;
  41         INIT_LIST_HEAD(&exec->unref_list);
  42
  43 -       mutex_lock(&dev->struct_mutex);
  44 -
  45         ret = vc4_cl_lookup_bos(dev, file_priv, exec);
  46         if (ret)
  47                 goto fail;
  48 @@ -636,15 +636,11 @@ vc4_submit_cl_ioctl(struct drm_device *d
  49         /* Return the seqno for our job. */
  50         args->seqno = vc4->emit_seqno;
  51
  52 -       mutex_unlock(&dev->struct_mutex);
  53 -
  54         return 0;
  55
  56  fail:
  57         vc4_complete_exec(exec);
  58
  59 -       mutex_unlock(&dev->struct_mutex);
  60 -
  61         return ret;
  62  }
  63